Do speakers take time to warm up?

Don't know for sure. If you're serious though then you should know there's a range of things that do affect performance and do result in needing some time to settle before returning to equilibrium, ie peak performance. 

Moving wires around. The more of the wire is moved and the more its moved the greater the disturbance and the longer the settling time. If all you do is move the cables around just enough to disconnect and connect its pretty slight and fast- might not even notice or if you do back to normal in a few minutes. But if you disconnect both ends and coil the cable up, bigger difference and might take a few minutes to settle back in. 

I don't know that just a few weeks is long enough for a speaker. Times I have left mine off that long it seemed to be right back where it was within a normal amount of warm-up time. 

Your question is hard to answer because even if you're a skilled and experienced listener who has heard this stuff many times before, ie millercarbon, how would you know if its the caps without some way of removing them to test the idea? Why would you, anyway? I mean I know there's no end of OCD audiophiles. Can we ever really be sure audiophile isn't just another way of spelling navel gazer? If it sounds better warm and we know to warm it up what does it matter if its the wire or the cap if its all the same in the end?

I should have been clearer perhaps.

I just got some used Kef R100’s.  They were in transit for a week.  I’m not sure if they were in use before the seller shipped them or how long they’d been sitting around not in use.

I disconnected the speakers I ws using, gently put my speaker cables on the ground without twisting them all up.

Connected the Kefs and there was very little bass and the soundstage sucked.  Listened to them for an hour and thought  I had made a mistake.  Left for an hour (speakers were playing during that time) came back and the soundstage is huge and there is some pretty good bass now.

And I don’t mean subtle changes, it was really really noticeable.  I’ve never experienced something quite like that and I have been through tons of speakers 🤔

You are adjusting,  getting used to them again. Evey time a new speaker is put in there is an adjustment period. 

I was wondering about that, Douglas, but I’ve never experienced it to that effect before.  Must have been a combination of that and what roberjerman said.